Association of common C-reactive protein (CRP) gene polymorphisms with baseline plasma CRP levels and fenofibrate response: the GOLDN study

Association of high-sensitivity C-reactive protein and diabetic nephropathy in patients with type 2 diabetes: a Mendelian randomization study

INTRODUCTION

Observational studies support the relationship between C-reactive protein (CRP) level and diabetic nephropathy (DN) in patients with diabetes. The research question regarding whether the relationship between serum high-sensitivity C-reactive protein (hsCRP) level and DN is causal lacks experimental evidence. Therefore, this study aimed to evaluate the causality between hsCRP and DN based on Mendelian randomization (MR) analysis.

RESEARCH DESIGN AND METHODS

A total of 2332 participants with type 2 diabetes from the Taiwan Biobank database was analyzed. Genetic risk scores (GRSs), which comprise four validated CRP loci as two instrumental variables, were calculated as unweighted and weighted scores to evaluate the causal relationship of hsCRP with DN risk. The two-stage regression model was used to estimate OR and 95% CI.

RESULTS

The analyses of the observational study showed that the hsCRP level was significantly associated with DN after multivariate adjustment (adjusted OR 1.15; 95% CI 1.01 to 1.32). Unweighted/weighted GRSs for log-transformed hsCRP satisfied MR assumptions 1 and 3, respectively; that is, a significant association with hsCRP was observed but that with DN was absent (adjusted OR 1.00, 95% CI 0.92 to 1.09; 1.00, 0.72 to 1.39, respectively). The MR analyses demonstrated that a 1-unit increase in the log-transformed genetically predicted hsCRP by unweighted and weighted GRSs was associated with DN, demonstrating ORs of 1.80 (95% CI 1.51 to 2.14) and 1.67 (95% CI 1.40 to 1.98), respectively.

CONCLUSIONS

The current study provided experimental evidence that hsCRP level was causally related to DN. These findings suggest that the elevated hsCRP may be a causal risk factor for DN in patients with type 2 diabetes.

Family-based genome-wide association of inflammation biomarkers and fenofibrate treatment response in the GOLDN study

In this paper we analyzed whole-genome genetic information provided by GAW20 from the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study for family data. Lipid levels such as triglycerides (TGs) and high-density lipoprotein (HDL) are measured at different time points before and after administration of an anti-inflammatory drug fenofibrate. Apart from that, the data contain some covariates and whole-genome genotype information. We propose 2 novel approaches based on Henderson's iterative mixed model to identify associated loci corresponding to (a) inflammatory biomarkers like TGs and HDLs together over time, and (b) the response to fenofibrate treatment. We developed a mixed-model approach using both TG and HDL phenotypes at all 4 time points for a genetic association study whereas we used TGs only to study genetic association with response to the drug. We expect that use of complete family data in a longitudinal framework under a single model involving the appropriate correlation structures would be able to exploit the maximum possible information contained in the sample. Our analysis of whole-genome single nucleotide polymorphisms (SNPs) and genomic regions corresponding to drug treatment finds no significant locus after multiple correction. Arguably, the moderately small sample size of the data set, as compared to the sample size usually used in genome-wide association studies (GWAS), could be a reason for such a result. Nevertheless, we report the top 20 SNPs associated with the phenotypes, and the top 20 SNPs and genomic regions associated with a response to fenofibrate treatment. Application of our methods to larger GWAS and further functional validation of the reported top SNPs and genomic regions might provide important biological insight into the genetic constitution of the trait.

Immunogenetics of prostate cancer: a still unexplored field of study

The immune system is a double-edged sword with regard to the prostate cancer (PCa) battle. Immunogenetics, the study of the potential role of immune-related polymorphisms, is taking its first steps in the treatment of this malignancy. This review summarizes the most recent papers addressing the potential of immunogenetics in PCa, reporting immune-related polymorphisms associated with tumor aggressiveness, treatment toxicity and patients' prognosis. With some peculiarities, RNASEL, IL-6, IL-10, IL-1β and MMP7 have arisen as the most significant biomarkers in PCa treatment and management, having a potential clinical role. Validation prospective clinical studies are required to translate immunogenetics into precision treatment of PCa.

An epigenome-wide association study of inflammatory response to fenofibrate in the Genetics of Lipid Lowering Drugs and Diet Network

AIM

Fenofibrate, a PPAR-α inhibitor used for treating dyslipidemia, has well-documented anti-inflammatory effects that vary between individuals. While DNA sequence variation explains some of the observed variability in response, epigenetic patterns present another promising avenue of inquiry due to the biological links between the PPAR-α pathway, homocysteine and S-adenosylmethionine - a source of methyl groups for the DNA methylation reaction.

HYPOTHESIS

DNA methylation variation at baseline is associated with the inflammatory response to a short-term fenofibrate treatment.

METHODS

We have conducted the first epigenome-wide study of inflammatory response to daily treatment with 160 mg of micronized fenofibrate over a 3-week period in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN, n = 750). Epigenome-wide DNA methylation was quantified on CD4⁺ T cells using the Illumina Infinium HumanMethylation450 array.

RESULTS

We identified multiple CpG sites significantly associated with the changes in plasma concentrations of inflammatory cytokines such as high sensitivity CRP (hsCRP, 7 CpG sites), IL-2 soluble receptor (IL-2sR, one CpG site), and IL-6 (4 CpG sites). Top CpG sites mapped to KIAA1324L (p = 2.63E-10), SMPD3 (p = 2.14E-08), SYNPO2 (p = 5.00E-08), ILF3 (p = 1.04E-07), PRR3, GNL1 (p = 6.80E-09), FAM50B (p = 3.19E-08), RPTOR (p = 9.79e-07) and several intergenic regions (p < 1.03E-07). We also derived two inflammatory patterns using principal component analysis and uncovered additional epigenetic hits for each pattern before and after fenofibrate treatment.

CONCLUSION

Our study provides preliminary evidence of a relationship between DNA methylation and inflammatory response to fenofibrate treatment.

DNA methylation as a marker of response in rheumatoid arthritis

Rheumatoid arthritis (RA) is a complex disease affecting approximately 0.5-1% of the population. While there are effective biologic therapies, in up to 40% of patients, disease activity remains inadequately controlled. Therefore, identifying factors that predict, prior to the initiation of therapy, which patients are likely to respond best to which treatment is a research priority and DNA methylation is increasingly being explored as a potential theranostic biomarker. DNA methylation is thought to play a role in RA disease pathogenesis and in mediating the relationship between genetic variants and patient outcomes. The role of DNA methylation has been most extensively explored in cancer medicine, where it has been shown to be predictive of treatment response. Studies in RA, however, are in their infancy and, while showing promise, further investigation in well-powered studies is warranted.

Discovery and fine-mapping of loci associated with MUFAs through trans-ethnic meta-analysis in Chinese and European populations

MUFAs are unsaturated FAs with one double bond and are derived from endogenous synthesis and dietary intake. Accumulating evidence has suggested that plasma and erythrocyte MUFA levels are associated with cardiometabolic disorders, including CVD, T2D, and metabolic syndrome (MS). Previous genome-wide association studies (GWASs) have identified seven loci for plasma and erythrocyte palmitoleic and oleic acid levels in populations of European origin. To identify additional MUFA-associated loci and the potential functional variant at each locus, we performed ethnic-specific GWAS meta-analyses and trans-ethnic meta-analyses in more than 15,000 participants of Chinese and European ancestry. We identified novel genome-wide significant associations for vaccenic acid at FADS1/2 and PKD2L1 [log10(Bayes factor) ≥ 8.07] and for gondoic acid at FADS1/2 and GCKR [log10(Bayes factor) ≥ 6.22], and also observed improved fine-mapping resolutions at FADS1/2 and GCKR loci. The greatest improvement was observed at GCKR, where the number of variants in the 99% credible set was reduced from 16 (covering 94.8 kb) to 5 (covering 19.6 kb, including a missense variant rs1260326) after trans-ethnic meta-analysis. We also confirmed the previously reported associations of PKD2L1, FADS1/2, GCKR, and HIF1AN with palmitoleic acid and of FADS1/2 and LPCAT3 with oleic acid in the Chinese-specific GWAS and the trans-ethnic meta-analyses. Pathway-based analyses suggested that the identified loci were in unsaturated FA metabolism and signaling pathways. Our findings provide novel insight into the genetic basis relevant to MUFA metabolism and biology.

Reverse Translational Study of Fenofibrate's Observed Effects in Diabetes-Associated Retinopathy

Clinical trials suggest that fenofibrate reduces the progression of retinopathies in patients with type 2 diabetes. Furthermore, patients with retinopathies have elevated levels of inflammatory chemokines and dysfunctional retinal angiogenesis. Therefore, we investigated the effects of fenofibrate on the production of inflammatory chemokines and genes associated with angiogenesis. Retinal pigment epithelial cells (RPECs) were cultured with IL-1β and fenofibrate ranging from 1-50 μM. ENA-78, IL-8, and RANTES were measured in cell culture by ELISA. ENA-78, ABCA1, and ABCG1 gene expression were tested by RT-PCR. IL-1β significantly induced the production of ENA-78, IL-8, and RANTES. Fenofibrate at concentrations of 25-50 uM blunted the IL-1β induced production of ENA-78 (p < 0.05) with no significant effects on RANTES and IL-8. Fenofibrate also reduced the expression of the ENA-78 gene as well as ABCA1 and ABCG1, which are genes involved in angiogenesis. Fenofibrate decreases ENA-78 production and ABCA1/ABCG1 gene expression in RPECs.

Toward optimal set of single nucleotide polymorphism investigation before IVF

BACKGROUND

At present, the patient preparation for IVF needs to undergo a series of planned tests, including the genotyping of single nucleotide polymorphism (SNP) alleles of some genes. In former USSR countries, such investigation was not included in overwhelming majority of health insurance programs and paid by patient. In common, there are prerequisites to the study of more than 50 polymorphisms. An important faced task is to determine the optimal panel for SNP genotyping in terms of price/number of SNP.

MATERIALS AND METHODS

During 2009-2015 in the University Hospital of St. Petersburg State University, blood samples were analyzed from 550 women with different reproductive system disorders preparing for IVF and 46 healthy women in control group. In total, 28 SNP were analyzed in the genes of thrombophilia factors, folic acid cycle, detoxification system, and the renin-angiotensin system. The method used was real-time PCR.

RESULTS

A significant increase in the frequency of pathological alleles of some polymorphisms in patients with habitual failure of IVF was shown, compared with the control group. As a result, two options defined panels for optimal typing SNP before IVF were composed. Standard panel includes 8 SNP, 5 in thromborhilic factors, and 3 in folic acid cycle genes. They are 20210 G > A of FII gene, R506Q G > A of FV gene (mutation Leiden), -675 5G > 4G of PAI-I gene, L33P T > C of ITGB3 gene, -455 G > A of FGB gene, 667 C > T of MTHFR gene, 2756 A > G of MTR gene, and 66 A > G of MTRR gene. Extended panel of 15 SNP also includes 807 C > T of ITGA2 gene, T154M C > T of GP1BA gene, second polymorphism 1298 A > C in MTHFR gene, polymorphisms of the renin-angiotensin gene AGT M235T T > C and -1166 A > C of AGTR1 gene, polymorphisms I105V A > G and A114V C > T of detoxification system gene GSTP.

CONCLUSION

The results of SNP genotyping can be adjusted for treatment tactics and IVF, and also medical support getting pregnant. The success rate of IVF is increased as the result, especially in the group with the usual failure of IVF.

A genome-wide study of lipid response to fenofibrate in Caucasians: a combined analysis of the GOLDN and ACCORD studies

BACKGROUND

Fibrates are commonly prescribed for hypertriglyceridemia, but they also lower LDL cholesterol and increase HDL cholesterol. Large interindividual variations in lipid response suggest that some patients may benefit more than others and genetic studies could help identify such patients.

METHODS

We carried out the first genome-wide association study of lipid response to fenofibrate using data from two well-characterized clinical trials: the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study and the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Study. Genome-wide association study data from both studies were imputed to the 1000 Genomes CEU reference panel (phase 1). Lipid response was modeled as the log ratio of the post-treatment lipid level to the pretreatment level. Linear mixed models (GOLDN, N=813 from 173 families) and linear regression models (ACCORD, N=781) adjusted for pretreatment lipid level, demographic variables, clinical covariates, and ancestry were used to evaluate the association of genetic markers with lipid response. Among Caucasians, the results were combined using inverse-variance weighted fixed-effects meta-analyses. The main findings from the meta-analyses were examined in other ethnic groups from the HyperTG study (N=267 Hispanics) and ACCORD (N=83 Hispanics, 138 African Americans).

RESULTS

A known lipid locus harboring the pre-B-cell leukemia homeobox 4 (PBX4) gene on chromosome 19 is important for LDL cholesterol response to fenofibrate (smallest P=1.5×10). The main results replicated with nominal statistical significance in Hispanics from ACCORD (P<0.05).

CONCLUSION

Future research should evaluate the usefulness of this locus to refine clinical strategies for lipid-lowering treatments.

Association of the C-Reactive Protein Gene (CRP) rs1205 C>T Polymorphism with Aortic Valve Calcification in Patients with Aortic Stenosis

Elevation in C-reactive protein (CRP) levels have been shown in patients with aortic valve stenosis (AS). Minor allele of the CRP gene (CRP) rs1205 C>T polymorphism has been associated with lower plasma CRP concentrations in cohorts of healthy and atherosclerotic patients. Considering the existing similarities between atherosclerosis and AS, we examined the effect of CRP rs1205 C>T polymorphism on the AS severity. Three hundred consecutive Caucasian patients diagnosed with AS were genotyped for the rs1205 C>T polymorphism using the TaqMan assay. Severity of the AS was assessed using transthoracic echocardiography. The degree of calcification was analyzed semi-quantitatively. Carriers of the rs1205 T allele were characterized by elevated serum CRP levels (2.53 (1.51-3.96) vs. 1.68 (0.98-2.90) mg/L, p<0.001) and a higher proportion of the severe aortic valve calcification (70.4% vs. 55.1%, p=0.01) compared with major homozygotes. The effect of CRP rs1205 polymorphism on CRP levels is opposite in AS-affected than in unaffected subjects, suggesting existence of a disease-specific molecular regulatory mechanism. Furthermore, rs1205 variant allele predisposes to larger aortic valve calcification, potentially being a novel genetic risk marker of disease progression.

ABCD2 alters peroxisome proliferator-activated receptor α signaling in vitro, but does not impair responses to fenofibrate therapy in a mouse model of diet-induced obesity

Fenofibrate is a peroxisome proliferator-activated receptor (PPAR) α ligand that has been widely used as a lipid-lowering agent in the treatment of hypertriglyceridemia. ABCD2 (D2) is a peroxisomal long-chain acyl-CoA transporter that is highly induced by fenofibrate in the livers of mice. To determine whether D2 is a modifier of fibrate responses, wild-type and D2-deficient mice were treated with fenofibrate for 14 days. The absence of D2 altered expression of gene clusters associated with lipid metabolism, including PPARα signaling. Using 3T3-L1 adipocytes, which express high levels of D2, we confirmed that knockdown of D2 modified genomic responses to fibrate treatment. We next evaluated the impact of D2 on effects of fibrates in a mouse model of diet-induced obesity. Fenofibrate treatment opposed the development of obesity, hypertriglyceridemia, and insulin resistance. However, these effects were unaffected by D2 genotype. We concluded that D2 can modulate genomic responses to fibrates, but that these effects are not sufficiently robust to alter the effects of fibrates on diet-induced obesity phenotypes.

Fenofibrate ameliorates insulin resistance, hypertension and novel oxidative stress markers in patients with metabolic syndrome

SUMMARY

OBJECTIVE

The benefits of fenofibrate, a peroxisome proliferator-activated receptor α agonist, against cardiovascular risk factors have been established. To clarify the underlying mechanisms of these benefits, we examined the effects of fenofibrate on insulin resistance, hypertension, inflammation, oxidative stress and coagulation markers in patients with metabolic syndrome.

METHODS

Eleven Japanese patients with metabolic syndrome underwent physical examinations and blood tests before and after treatment with fenofibrate 200 mg daily for 8 weeks.

RESULTS

Fenofibrate significantly decreased systolic blood pressure, pulse wave velocity, serum insulin, insulin resistance (calculated from the homeostasis model assessment), total cholesterol, triglyceride, remnant-like particles cholesterol, uric acid, D-dimer, fibrinogen, serum amyloid A/low-density lipoprotein (LDL) and apoA1/LDL levels. It also significantly increased levels of high molecular weight adiponectin, thrombomodulin and high-density lipoprotein cholesterol in these patients. Plasminogen activator inhibitor-1, C-reactive protein, fasting plasma glucose and thrombin-antithrombin complex levels did not change.

LIMITATION

Small sample size.

CONCLUSION

Short-term fenofibrate administration not only improved lipid profiles, but also ameliorated insulin resistance, hypertension and oxidative stress markers in patients with metabolic syndrome, suggesting that fenofibrate can decrease the risk of arteriosclerosis through various pathways.

Profiling serum bile acid glucuronides in humans: gender divergences, genetic determinants, and response to fenofibrate

Glucuronidation, catalyzed by UDP-glucuronosyltransferase (UGT) enzymes detoxifies cholestatic bile acids (BAs). We aimed at i) characterizing the circulating BA-glucuronide (-G) pool composition in humans, ii) evaluating how sex and UGT polymorphisms influence this composition, and iii) analyzing the effects of lipid-lowering drug fenofibrate on the circulating BA-G profile in 300 volunteers and 5 cholestatic patients. Eleven BA-Gs were determined in pre- and post-fenofibrate samples. Men exhibited higher BA-G concentrations, and various genotype/BA-G associations were discovered in relevant UGT genes. The chenodeoxycholic acid-3G concentration was associated with the UGT2B7 802C>T polymorphism. Glucuronidation assays confirmed the predominant role of UGT2B7 and UGT1A4 in CDCA-3G formation. Fenofibrate exposure increased the serum levels of 5 BA-G species, including CDCA-3G, and up-regulated expression of UGT1A4, but not UGT2B7, in hepatic cells. This study demonstrates that fenofibrate stimulates BA glucuronidation in humans, and thus reduces bile acid toxicity in the liver.

Pharmacogenomics of lipid-lowering therapies

Statins are the most widely used group of lipid-lowering drugs and they have been shown to be effective in the prevention of cardiovascular disease, primarily by reducing plasma low-density lipoprotein cholesterol concentrations and possibly through other pleiotropic effects. However, there are large variations in lipid responses to statins and some patients have intolerable muscle adverse drug reactions, which may in part be related to genetic factors. In the last decade, pharmacogenetic studies on statins ranging from the candidate gene approach to the more recent genome-wide association studies have provided evidence that genetic variations play an important role in determining statin responses. This review summarizes the current understanding on the pharmacogenomics of statins and other lipid-lowering drugs in current use.

C-reactive protein 1059G/C gene polymorphism, C-reactive protein levels and acute myocardial infarction

AIMS

High-sensitivity C-reactive protein (hs-CRP) is an inflammatory marker, predicting the occurrence of acute myocardial infarction (AMI). Genetic predisposition to high baseline CRP might account for a high risk of heart diseases. Our study aimed at investigating an association of CRP 1059G/C gene polymorphism with plasma CRP levels and AMI in Egyptian patients.

METHODS

Genotypes of 150 patients with AMI and 150 healthy sex and age-matched controls were analyzed using PCR-restriction fragment length polymorphism methods. hs-CRP concentrations were assessed.

RESULTS

There was no significant association between CRP 1095G/C polymorphism and AMI. However, individuals with GG genotype had significantly higher plasma CRP concentration than those with GC and CC genotypes, in both controls (3.82 ± 1.03 vs. 2.34 ± 0.7; P = 0.001) and patients with AMI (8.39 ± 2.6 vs. 6.67 ± 2.4; P = 0.005).

CONCLUSION

Our results revealed that CRP 1059G/C gene variation influences plasma CRP levels. Conversely, this polymorphism was not associated with the risk for AMI.

Modulatory effect of fenofibrate on endothelial production of neutrophil chemokines IL-8 and ENA-78

PURPOSE

The PPAR-alpha agonists (fibrates) are commonly used in the treatment of dyslipidemia. It has been hypothesized that the cardio-protective effects of fibrates are partially due to immunomodulatory effects. However, there is a paucity of data regarding the effect of fibrates on neutrophilic chemokines such as epithelial neutrophil activating protein (ENA-78) and interleukin (IL)-8. We investigated the influence of fenofibrate on IL-1β-stimulated production of ENA-78 and IL-8 from human endothelial cells (HUVECs).

METHODS

HUVECs were cultured in the presence or absence of IL-1β and fenofibrate ranging from 1-50 uM. ENA-78 and IL-8 were measured and normalized to total protein content in cell culture supernates by multiplex immunofluorescence detection. Experimental samples were measured in triplicate. Significance was set at P < 0.05 by ANOVA with correction for multiple comparisons.

RESULTS

Endothelial production of both ENA-78 and IL-8 was induced by the proinflammatory cytokine IL-1β. ENA-78 concentrations increased by more than 160-fold over constitutively produced ENA-78 upon IL-1β stimulation (mean ± SEM: 10,129 ± 1591 pg/mg vs. 61 ± 9.5 mg/mg; P < 0.0001). IL-8 concentrations increased by slightly over 5-fold (6145 ± 860 pg/mg vs. 1160 ± 201 pg/mg; P = 0.0003). ENA-78 protein and mRNA were significantly reduced by fenofibrate while no drug effects were observed on IL-8 production.

CONCLUSIONS

Fenofibrate blunts IL-1β-mediated ENA-78 production with no effect on IL-8. This represents a novel mechanism by which fenofibrate exerts anti-inflammatory effects and should be further explored.

A genome-wide association study of inflammatory biomarker changes in response to fenofibrate treatment in the Genetics of Lipid Lowering Drug and Diet Network

OBJECTIVE

Despite the evidence in support of the anti-inflammatory and triglyceride-lowering effects of fenofibrate, little is known about genetic determinants of the observed heterogeneity in treatment response. This study provides the first genome-wide examination of fenofibrate effects on systemic inflammation.

METHODS

Biomarkers of inflammation were measured in participants of the Genetics of Lipid Lowering Drugs and Diet Network (n=1092) before and after a 3-week daily treatment with 160 mg of fenofibrate. Two inflammatory patterns [high-sensitivity C-reactive protein-interleukin-6 and monocyte chemoattractant protein-1-tumor necrosis factor (MCP1-TNF-α)] were derived using principal component analysis. Associations between single nucleotide polymorphisms on the Affymetrix 6.0 chip and phenotypes were assessed using mixed linear models, adjusted for age, sex, study center, and ancestry as fixed effects and pedigree as a random effect.

RESULTS

Before fenofibrate treatment, the strongest evidence for association was observed for polymorphisms near or within the IL2RA gene with the high-sensitivity C-reactive protein-interleukin-6 (IL6) pattern (rs7911500, P=5×10 and rs12722605, P=5×10). Associations of the MCP1-TNF-α pattern with loci in several biologically plausible genes [CYP4F8 (rs3764563), APBB1IP (rs1775246), COL13A1 (rs2683572), and COMMD10 (rs1396485)] approached genome-wide significance (P=3×10, 5×10, 6×10, and 7×10, respectively) before fenofibrate treatment. After fenofibrate treatment, the rs12722605 locus in IL2RA was also associated with the MCP1-TNF-α pattern (P=3×10). The analyses of individual biomarker response to fenofibrate did not yield genome-wide significant results, but the rs6517147 locus near the immunologically relevant IFNAR2 gene was suggestively associated with IL6 (P=7×10).

CONCLUSION

We have identified several novel biologically relevant loci associated with systemic inflammation before and after fenofibrate treatment.

The PPAR alpha gene is associated with triglyceride, low-density cholesterol and inflammation marker response to fenofibrate intervention: the GOLDN study

As a peroxisome proliferator-activated receptor alpha (PPARα) agonist, fenofibrate favorably modulates dyslipidemia and inflammation markers, which are associated with cardiovascular risk. To determine whether variation in the PPARα receptor gene was associated with lipid and inflammatory marker response, we conducted a three week trial of fenofibrate in 861 men and women. Mixed linear models which controlled for age and sex, as well as family pedigree and study-center, were constructed using SNPs in the PPARα gene as predictors and changes in fasting triglycerides (TGs), cholesterol and inflammatory markers as outcomes. Significant associations with low-density cholesterol (LDL-C) and interleukin-2 (IL-2; P<.001) responses to fenofibrate were found. Although there were suggestive associations with tumour necrosis factor-alpha (TNF-α) and TG responses (P<.05), these did not survive the correction for multiple testing. We conclude that variants in the PPARα gene may contribute to future pharmacogenomic paradigms seeking to predict fenofibrate responders from both an anti-dyslipidemic and anti-inflammatory perspective.

Metabolomic profiling of 17 bile acids in serum from patients with primary biliary cirrhosis and primary sclerosing cholangitis: a pilot study

BACKGROUND

Primary biliary cirrhosis and primary sclerosing cholangitis are two cholestatic diseases characterised by hepatic accumulation of bile acids.

AIMS

This study compares serum bile acid levels in patients with primary biliary cirrhosis and primary sclerosing cholangitis and from age and sex-matched non cholestatic donors.

METHODS

Seventeen bile acids were quantified using liquid chromatography coupled to tandem mass spectrometry. Serum samples from cholestatic patients were compared with those of non-cholestatic donors.

RESULTS

The concentration of total bile acids, taurine and glycine conjugates of primary bile acids was elevated in both patients with primary biliary cirrhosis and primary sclerosing cholangitis when compared to non-cholestatic donors. Samples from primary sclerosing cholangitis patients displayed reduced levels of secondary acids, when compared to non cholestatic and primary biliary cirrhosis sera. The ratio of total glycine versus total taurine conjugates was reduced in patients with primary biliary cirrhosis, but not in primary sclerosing cholangitis.

CONCLUSION

The present study suggests that circulating bile acids are altered differentially in primary biliary cirrhosis and primary sclerosing cholangitis patients.

The polymorphisms of C-reactive protein gene modify the association between central obesity and lung function in taiwan asthmatics

High-sensitivity C-reactive protein (hs-CRP) concentrations and obesity are proposed to have a significant relationship with impairment of lung function, but little has been reported to date on the association between CRP gene and lung function. We studied the association of three tagSNPs (tag single nucleotide polymorphisms) of CRP gene and their interactions with central obesity on lung function. A total of 384 asthmatic adults and 384 controls who were 1:1 matched by sex and age were recruited for this study. Three tagSNPs polymorphisms for CRP rs1417938, rs1800947 and rs1205 were selected from HapMap data and genotyping by using TaqMan allelic discrimination assay. A questionnaire interview, body composition and pulmonary function tests were performed. CRP single nucleotide polymorphisms (SNPs) did not increase the risk of asthma, but CRP rs1205 CC genotype significantly decreased the predictive value of forced vital capacity (FVC) in the asthma group (adjusted mean change = -7.54%, 95% CI = -13.82 to -1.25%). Waist-to-hip ratio, not body mass index, also decreased the predictive value of FVC in asthmatics. The subjects with central obesity who carried CRP SNPs have a significant reduction effect in lung function. The current results suggest that central obesity may play a major role in lung function, and these effects were modified significantly by the polymorphisms for CRP gene.

Volume of white matter hyperintensities in healthy adults: contribution of age, vascular risk factors, and inflammation-related genetic variants

Aging is associated with appearance of white matter hyperintensities (WMH) on MRI scans. Vascular risk and inflammation, which increase with age, may contribute to white matter deterioration and proliferation of WMH. We investigated whether circulating biomarkers and genetic variants associated with elevated vascular risk and inflammation are associated with WMH volume in healthy adults (144 volunteers, 44-77 years of age). We examined association of WMH volume with age, sex, hypertension, circulating levels of total plasma homocysteine (tHcy), cholesterol (low-density lipoprotein), and C-reactive protein (CRP), and four polymorphisms related to vascular risk and inflammation: Apolipoprotein ε (ApoE ε2,3,4), Angiotensin-Converting Enzyme insertion/deletion (ACE I/D), methylenetetrahydrofolate reductase (MTHFR) C677T, C-reactive protein (CRP)-286C>A>T, and interleukin-1β (IL-1β) C-511T. We found that larger WMH volume was associated with advanced age, hypertension, and elevated levels of homocysteine and CRP but not with low-density lipoprotein levels. Homozygotes for IL-1β-511T allele and carriers of CRP-286T allele that are associated with increased inflammatory response had larger WMH than the other allelic combinations. Carriers of the APOE ε2 allele had larger frontal WMH than ε3 homozygotes and ε4 carriers did. Thus, in healthy adults, who are free of neurological and vascular disease, genetic variants that promote inflammation and elevated levels of vascular risk biomarkers can contribute to brain abnormalities. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

Profiling circulating and urinary bile acids in patients with biliary obstruction before and after biliary stenting

Bile acids are considered as extremely toxic at the high concentrations reached during bile duct obstruction, but each acid displays variable cytotoxic properties. This study investigates how biliary obstruction and restoration of bile flow interferes with urinary and circulating levels of 17 common bile acids. Bile acids (conjugated and unconjugated) were quantified by liquid chromatography coupled with tandem mass spectrometry in serum and urine samples from 17 patients (8 men and 9 women) with biliary obstruction, before and after biliary stenting. Results were compared with serum concentrations measured in 40 age- and sex-paired control donors (20 men and 20 women). The total circulating bile acid concentration increases from 2.7 µM in control donors to 156.9 µM in untreated patients with biliary stenosis. Serum taurocholic and glycocholic acids exhibit 304- and 241-fold accumulations in patients with biliary obstruction compared to controls. The enrichment in chenodeoxycholic acid species reached a maximum of only 39-fold, while all secondary and 6α-hydroxylated species--except taurolithocholic acids--were either unchanged or significantly reduced. Stenting was efficient in restoring an almost normal circulating profile and in reducing urinary bile acids.

CONCLUSION

These results demonstrate that biliary obstruction affects differentially the circulating and/or urinary levels of the various bile acids. The observation that the most drastically affected acids correspond to the less toxic species supports the activation of self-protecting mechanisms aimed at limiting the inherent toxicity of bile acids in face of biliary obstruction.

Profile of serum bile acids in noncholestatic volunteers: gender-related differences in response to fenofibrate

Fenofibrate belongs to hypolipidemic fibrates that act as activators of the peroxisome proliferator-activated receptor-α, a regulator of bile acid synthesis, metabolism and transport. The present study aimed at evaluating the effects of fenofibrate on the circulating bile acid profile in humans. Hundred healthy men and women completed a 3-week intervention with fenofibrate, and 17 bile acid species were measured in serum samples drawn before and after fenofibrate treatment. Fenofibrate caused significant reductions in levels of chenodeoxycholic (−26.4%), ursodeoxycholic (−30.5%), lithocholic (−18.4%), deoxycholic (−22.3%) and hyodeoxycholic (−19.2%) acids. A gender-related difference was observed in the response of various bile acids and the total bile acid concentration was significantly reduced only in men (−18.6%), while remaining almost unchanged in women (+0.36%). This difference detected suggests that fenofibrate should be more efficient at reducing bile acid toxicity in men than in women in cholestatic liver diseases.

Genetic variation in C-reactive protein in relation to colon and rectal cancer risk and survival

C-reactive protein (CRP), a biomarker of inflammation, has been shown to be influenced by genetic variation in the CRP gene. In this study, we test the hypothesis that genetic variation in CRP influences both the risk of developing colon and rectal cancer and survival. Two population-based studies of colon cancer (n = 1,574 cases, 1,970 controls) and rectal (n = 791 cases, 999 controls) were conducted. We evaluated four CRP tagSNPs: rs1205 (G > A, 3' UTR); rs1417938 (T > A, intron); rs1800947 (G > C, L184L); and rs3093075 (C > A, 3' flanking). The CRP rs1205 AA genotype was associated with an increased risk of colon cancer (OR 1.3, 95%CI 1.1-1.7), whereas the rs3093075 A allele was associated with a reduced risk of rectal cancer (OR 0.7, 95%CI 0.5-0.9). The strongest association for the rs1205 polymorphism and colon cancer was observed among those with KRAS2 mutations (OR 1.5, 95%CI 1.1-2.0). The CRP rs1205 AA genotype also was associated with an increased risk of CIMP+ rectal tumors (OR 2.5, 95%CI 1.2-5.3); conversely, the rs1417938 A allele was associated with a reduced risk of CIMP+ rectal tumors (OR 0.5, 95%CI 0.3-0.9). We observed interactions between CRP rs1800947 and BMI and family history of CRC in modifying risk of both colon and rectal cancer. These data suggest that genetic variation in the CRP gene influences risk of both colon and rectal cancer development.

Genetic polymorphisms influence runners' responses to the dietary ingestion of antioxidant supplementation based on pequi oil (Caryocar brasiliense Camb.): a before-after study

Genes have been implicated in the levels of oxidative stress, lipids, CVD risk, immune reactivity, and performance. Pequi oil (Caryocar brasiliense) has shown anti-inflammatory and hypotensive effects, besides reducing exercise-induced DNA, tissue damages, and anisocytosis. Given that diet can interact with the human genome to influence health and disease, and because genetic variability can influence response to diet, we aim to investigate the influence of 12 gene polymorphisms on inflammatory markers, postprandial lipids, arterial pressure, and plasma lipid peroxidation of runners (N = 125), before and after 14 days of 400 mg pequi-oil supplementation, after races under closely comparable conditions. Arterial pressure was checked before races; blood samples were taken immediately after racing to perform leukogram and plateletgram, Tbars assay, lipid, and CRP dosages and genotyping. CAT, GST-M1/T1, CRP-G1059C, and MTHFR-C677T polymorphisms influenced post-pequi-oil responses in leukogram; Hp and MTHFR-C677T, in plateletgram; Hp, ACE, GSTT1, and MTHFR-A1298C, in lipid profile; MTHFR-A1298C, in C-reactive protein (CRP) levels; and Hp and MnSOD, in Tbars assay. Differences between ACE genotypes in leukogram and total cholesterol disappeared after pequi, and the same occurred for Hp and MnSOD in Tbars assay and for MTHFR-A1298C with CRP levels. Because genetic inheritance is one of the factors that drive atherosclerosis-related lipid abnormalities, results can contribute to a greater understanding of the influence of genetic polymorphisms in situations that push up free radicals. Knowledge is also expanded on how antioxidant supplementation affects an individual's genes and how athletic genetic makeup can affect the way a person responds to antioxidant supplements.

Association of C-reactive protein gene polymorphisms and colorectal cancer

BACKGROUND

An elevated plasma level of C-reactive protein (CRP) is a risk for, and prognostic factor of, colorectal cancer (CRC). In other reports of CRP concerning cardiovascular disease, CRP level correlated with its gene polymorphisms. We hypothesized that CRP polymorphisms associate risk and prognosis of CRC.

METHODS

This study enrolled 421 patients with CRC and 218 healthy control subjects. After preliminary studies, we selected four single nucleotide polymorphisms (SNPs) in the CRP gene: +2147A > G (rs1205), +942G > C (rs1800947), -717A > G (rs2794521), and -757T > C (rs3093059). At first, analyzing distributions of four SNPs between CRC case and non-CRC control groups was performed. Subsequently, the impacts of these SNPs with other prognostic factors of disease-free interval (DFI) and cancer-specific survival (CSS) were analyzed using uni- and multivariate Cox regression analyses.

RESULTS

The case and control groups differed in the frequency of -757T > C (P = 0.002). The CRC case group had a higher percentage of the TT genotype (odds, 1.75). Regarding prognoses, multivariate analyses revealed that four factors, including stage (I, II, III), gross tumor type (polypoid, ulcerative, infiltrative), location (right, left, rectum), and -757T > C SNP (odds, 1.29; P = 0.048), correlated with DFI; two factors, including stage and +2147A > G SNP (odds, 0.71; P = 0.03), correlated with CSS.

CONCLUSIONS

The -757T > C SNP is a risk for and prognostic factor of DFI; the +2147A > G SNP is a prognostic factor of CSS. CRP polymorphisms associate the risk and survival of CRC.

Fenofibrate and metabolic syndrome

The fibric acid derivative, fenofibrate (FF) has been used in the US since 1998 to manage patients with dyslipidemia. Typical changes in serum lipids as result a of FF treatment include clinically important mean reductions of serum triglycerides (TG) by a mean change of -93.7 mg/dL (-39.3%), increases of high density lipoprotein cholesterol (HDLC) by +5.5 mg/dL (+12.4%), and reductions in low density lipoprotein cholesterol (LDLC) by -17.9 mg/dL (-12.3%). The greatest reductions in serum TG are usually observed in subjects with elevated baseline TGs including those with the metabolic syndrome (MetS). Although statins remain the mainstay of therapy for most dyslipidemic patients, their combined use with FF would be expected to address residual risk resulting from less than optimal TG and HDLC levels in such patients. Clinical trials examining the cardiovascular benefits of FF alone or combined with statins have produced mixed results. These observations underscore our lack of understanding of which patients may benefit from FF therapy and which do not. Although FF's basic mechanism of action is known to involve PPAR-alpha agonist activity resulting in altered transcription of several genes, the actual genetic bases for variability in lipid response is poorly understood. Studies, such as our GOLDN study and others designed to better understand the genetic determinants of variability in the response to FF treatment and lipid levels. As a result several important genetic determinants of lipid levels have been identified. For example, in the GOLDN study SNPs from different genes were significantly associated with baseline lipid levels before treatment (APOA5- rs662799, rs3135506; APOC3- rs5128, rs2854117, rs4520); APOA4- rs5104; PPARA- rs9626730, rs135543, rs11703495; LPL- rs1801177), after treatment PPARA- rs11708495; LPL- rs1801177, and appeared to modulate overall response to FF treatment (NOS3- rs1799983). In this article, we will review the literature leading up to the contemporary use of FF as an agent to manage patients with dyslipidemia and focus on emerging understanding of the genetic variability in response to FF treatment. On the basis of the available evidence, we conclude that FF is of benefit in the treatment of dyslipidemia, especially among those with MetS. However, more work is needed to specifically identify which individuals derive a benefit from FF administration in terms of clinical outcomes and which do not - particularly in the context of type 2 diabetes.

High-sensitivity C-reactive protein predicts mortality but not stroke: the Northern Manhattan Study

OBJECTIVE

To determine whether high-sensitivity C-reactive protein (hsCRP) and serum amyloid A (SAA) predict stroke, vascular events, and mortality in a prospective cohort study.

BACKGROUND

Markers of inflammation have been associated with risk of myocardial infarction (MI). Their association with stroke is controversial.

METHODS

The Northern Manhattan Study includes a stroke-free community-based cohort study in participants aged > or =40 years (median follow-up 7.9 years). hsCRP and SAA were measured using nephelometry. Cox proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for the association of markers with risk of ischemic stroke and other outcomes after adjusting for demographics and risk factors.

RESULTS

hsCRP measurements were available in 2,240 participants (mean age 68.9 +/- 10.1 years; 64.2% women; 18.8% white, 23.5% black, and 55.1% Hispanic). The median hsCRP was 2.5 mg/L. Compared with those with hsCRP <1 mg/L, those with hsCRP >3 mg/L were at increased risk of ischemic stroke in a model adjusted for demographics (HR = 1.60, 95% CI 1.06-2.41), but the effect was attenuated after adjusting for other risk factors (adjusted HR = 1.20, 95% CI 0.78-1.86). hsCRP >3 mg/L was associated with risk of MI (adjusted HR = 1.70, 95% CI 1.04-2.77) and death (adjusted HR = 1.55, 95% CI 1.23-1.96). SAA was not associated with stroke risk.

CONCLUSION

In this multiethnic cohort, high-sensitivity C-reactive protein (hsCRP) was not associated with ischemic stroke, but was modestly associated with myocardial infarction and mortality. The value of hsCRP and serum amyloid A may depend on population characteristics such as age and other risk factors.

Inflammation as a cardiovascular risk factor and pulse wave velocity as a marker of early-stage atherosclerosis in the Japanese population

Inflammation and pulse wave velocity (PWV) are a potential risk factor and marker, respectively, for atherosclerosis in the primary prevention setting. Atherosclerosis is now generally accepted to be an inflammatory disorder of the arterial wall, and the high-sensitivity C-reactive protein (hs-CRP) level has been reported to be a strong predictor of cardiovascular events. High-sensitivity-CRP is associated with two factors related to inflammation: (1) the local production of CRP by atheromatous tissue or coronary artery smooth muscle cells and (2) adipose tissue as a potent source of inflammatory cytokines. Based on studies in North America and Europe, hs-CRP has been established as a cardiovascular risk factor and a cut-off value has been recommended. However, Japanese have lower hs-CRP values than their Western counterparts, partly because Japanese have a lower body mass index (BMI), which correlates positively to hs-CRP, and partly because lifestyle and genetic factors can affect hs-CRP values. Therefore, a cut-off value needs to be established by cohort studies for the Japanese population. Carotid-femoral PWV is most commonly measured by applanation tonometry, particularly in Europe, but this method is critically dependent upon the accurate placing of transducers over the arteries and is both time-consuming and complex. A novel device has been recently developed in Japan that measures brachial-ankle PWV (baPWV) using a volume-rendering method. Brachian-ankle PWV is a suitable screening method because of its technical simplicity and shorter measurement time. It is associated not only with conventional cardiovascular risk factors but also with new risk factors, such as inflammation, gamma-glutamyltransferase, chronic kidney disease, and psychosocial factors. However, a suitable cut-off value has yet to be established.

Genome-wide association study of plasma polyunsaturated fatty acids in the InCHIANTI Study

Polyunsaturated fatty acids (PUFA) have a role in many physiological processes, including energy production, modulation of inflammation, and maintenance of cell membrane integrity. High plasma PUFA concentrations have been shown to have beneficial effects on cardiovascular disease and mortality. To identify genetic contributors of plasma PUFA concentrations, we conducted a genome-wide association study of plasma levels of six omega-3 and omega-6 fatty acids in 1,075 participants in the InCHIANTI study on aging. The strongest evidence for association was observed in a region of chromosome 11 that encodes three fatty acid desaturases (FADS1, FADS2, FADS3). The SNP with the most significant association was rs174537 near FADS1 in the analysis of arachidonic acid (AA; p = 5.95×10⁻⁴⁶). Minor allele homozygotes had lower AA compared to the major allele homozygotes and rs174537 accounted for 18.6% of the additive variance in AA concentrations. This SNP was also associated with levels of eicosadienoic acid (EDA; p = 6.78×10⁻⁹) and eicosapentanoic acid (EPA; p = 1.07×10⁻¹⁴). Participants carrying the allele associated with higher AA, EDA, and EPA also had higher low-density lipoprotein (LDL-C) and total cholesterol levels. Outside the FADS gene cluster, the strongest region of association mapped to chromosome 6 in the region encoding an elongase of very long fatty acids 2 (ELOVL2). In this region, association was observed with EPA (rs953413; p = 1.1×10⁻⁶). The effects of rs174537 were confirmed in an independent sample of 1,076 subjects participating in the GOLDN study. The ELOVL2 SNP was associated with docosapentanoic and DHA but not with EPA in GOLDN. These findings show that polymorphisms of genes encoding enzymes in the metabolism of PUFA contribute to plasma concentrations of fatty acids.

Polyunsaturated fatty acids (PUFA) have a number of beneficial effects on human health. Plasma PUFA concentrations are determined by a combination of dietary intake and metabolic efficiency. To determine the genes involved in PUFA homeostasis, we scanned the genome for genetic variations associated with plasma PUFA concentrations. The fatty acid desaturase gene, studied in previous candidate gene association studies, was the strongest determinant of plasma PUFA. A second gene encoding a fatty acid elongase was associated with long chain PUFA. The results of this study contribute to our understanding of the genetics of PUFA homeostasis. These genetic markers may be useful tools to examine the inter-relationship between diet, genetics, and disease.

Impact of genetic and environmental factors on hsCRP concentrations and response to therapeutic agents

BACKGROUND

Inflammation plays an instrumental role in all stages of atherosclerosis. High-sensitivity C-reactive protein (hsCRP), a systemic inflammatory marker, has been gaining recognition as an independent risk factor for cardiovascular disease (CVD). Both baseline hsCRP concentrations and drug-induced hsCRP changes are highly variable and potentially subject to genetic regulation.

CONTENT

This review summarizes the current studies examining the effect of genetic and environmental factors on baseline plasma hsCRP concentrations, with a main focus on C-reactive protein, pentraxin-related (CRP) genetic polymorphisms and various dietary components that affect hsCRP concentrations. We also address the association of CRP genetic variations with CVD risk, a relationship that may support or refute the causality of CRP in the atherosclerotic process. Moreover, we discuss the impact of CRP genetic polymorphisms on hsCRP changes in response to 3-week fenofibrate treatment in the genetic intervention of the Genetics of Lipid Lowering Drugs and Diet Network study.

SUMMARY

Genetic variants on the CRP locus and other loci and dietary and lifestyle factors are responsible for the interindividual variability of plasma hsCRP concentrations. CRP genetic variants further influence differing plasma hsCRP response after 3-week fenofibrate treatment in patients with metabolic syndrome. Future studies focusing on the influence and interaction of genetic variation on the hsCRP response to dietary and other behavior modification as well as drug treatment could have important implications for the development of more personalized preventive and therapeutic approaches to reduce CVD.

Association between C-reactive protein gene haplotypes and C-reactive protein levels in Taiwanese: interaction with obesity

OBJECTIVE

The level of C-reactive protein (CRP), an inflammatory marker that predicts future cardiovascular events, is a heritable trait. Our aim was to test the statistical associations between variations in the CRP gene and serum CRP levels in a Taiwanese population with interaction analysis.

METHODS

A sample population of 617 Taiwanese subjects was enrolled. Five CRP single nucleotide polymorphisms (SNPs) previously reported to be associated with CRP level and with reasonable coverage of the CRP gene region were analyzed using polymerase chain reaction and restriction enzyme digestion or by TaqMan SNP Genotyping Assays.

RESULTS

After adjusting for clinical covariates, minor alleles of 3 of the 5 SNPs were associated with change in CRP level: rs3091244 and rs1205 were associated with increased CRP level (P=0.001 and P<0.001, respectively) and rs1800947 with decreased CRP level (P=0.003). Two haplotypes inferred from 5 SNPs (GCGCG and AAGCG) were associated with increased CRP level (P=0.017 and P<0.0001, respectively). Interaction analysis revealed interaction of obesity with CRP genotypes associated with high CRP level (interaction P=0.034 and 0.020 for SNPs rs2794521 and rs1800947, respectively). An effect of obesity on CRP level was also noted in haplotype interaction analysis with the association occurring predominantly in obese subjects (P=0.034).

CONCLUSION

CRP polymorphisms are independently associated with increased or decreased CRP level in Taiwanese. Further, CRP genotypes/haplotypes interact with obesity to set CRP level. These findings have implications for the prediction of atherosclerotic disease.

Gene-environment interactions and susceptibility to metabolic syndrome and other chronic diseases

There is an intrinsic complexity in the pathogenesis of common diseases. The concept of gene-environment interaction is receiving support from emerging evidence coming primarily from studies involving diet and cardiovascular disease (CVD) and its various risk factors. The accumulating evidence shows that common variants at candidate genes for lipid metabolism, inflammation, and obesity are associated with altered plasma levels of classic and new biomarkers of metabolic syndrome and CVD risk. Major contributors to this knowledge have been a series of large population studies containing phenotype-rich databases and dietary information to which genetic data have been added. Although this approach has provided strong evidence supporting the concept of gene-diet interactions modulating CVD risk factors, the strength of the individual effect is very small, and the replication among studies is rather disappointing. Current population studies are starting to incorporate experimental and analytical approaches that could provide more solid and comprehensive results. However, other limitations, such as the size of the populations required to examine higher-level interactions, are still major obstacles to translating this knowledge into practical public health applications. Nevertheless, data from numerous molecular and genetic epidemiological studies provide tantalizing evidence suggesting that gene-environment interactions, i.e., the modulation by a genetic polymorphism of a dietary component effect on a specific phenotype (e.g., cholesterol levels and obesity), can interact in ways that increase the risk for developing chronic disease, including susceptibility to developing the metabolic syndrome. Once further experience is gained from patients and/or individuals at high risk, more personalized genetic-based approaches may be applied toward the primary prevention and treatment of CVDs and other complex inflammatory diseases.